Bangkok, Thailand (BBN)– Asia’s coastal megacities will flood more often, on a larger scale, and affect millions more people, if current climate change trends continue, a new report said on Friday.

The report Climate Risks and Adaptation in Asian Coastal Megacities examines the impact of climate change on Bangkok, Ho Chi Minh City, and Manila, under a range of different scenarios through to 2050.

The report is the product of a two-year collaborative study by the Asian Development Bank (ADB), the Japan International Cooperation Agency (JICA) and the World Bank. It was released on the day at the Asia Pacific Climate Change Adaptation Forum.

The report finds that costs from major flooding events on infrastructure and the economy could run into the billions of dollars, with urban poor populations likely to be the hardest hit. It concludes that all three cities need to take targeted, city-specific and cutting edge approaches to meet these challenges.

Bangkok, Ho Chi Minh City, and Manila all have populations close to or over 10 million. Two are capital cities and all three are centers of national and regional economic growth contributing substantially to the gross domestic product (GDP) of the respective countries. As coastal megacities, all face increased climate related risks such as rising sea levels and an increased frequency of extreme weather events.

While commendable measures to counteract flooding have already been taken by these cities, much more needs to be done, the report added.

For cities to address future climate related risks, sound urban environmental management is crucial. Land subsidence due to groundwater pumping, dumping of solid waste into city canals and waterways, clogged drainage systems, and deforestation in the upper watershed all contribute to urban flooding.

“Better management of these urban environmental issues will help manage future climate-related impacts,” it noted.

BBN/SSR/AD-23Oct10-1:44 am (BST)